We are continuing to develop a model for the evaluation of the contribution of collateral sprouting of the processes of dorsal root ganglion cells to altered function or recovery following lesions of the spinal cord. We now can manipulate sciatic and saphenous central axons in order to examine, at the light and EM levels, alterations in their central terminal fields that occur following lesions. We have concentrated this year on the ultrastructural changes in afferent terminals, target dendrites and somata, and glia formations that occur in the dorsal horn following rhizotomy, sciatic nerve section, or specific degeneration of sciatic central terminals often injection of the sciatic nerve with pronase. We will now carry out experiments to examine the possible collateral sprouting of saphenous afferents into the sciatic territory following destruction of the sciatic afferents. Documentation of the changes will be carried out with both light and EM analysis.